Perfect Amulet

The Perfect Amulet is an ornate amulet which serves as a key to the Temen-ni-gru's gate to the Demon World, and is also necessary to awaken the Force Edge. A large red gem is set into the amulet, and it can be split into two halves. It was given as a gift to Eva by Sparda, and she gave the halves to their twin sons , Dante and Vergil, on their birthday. Their names are engraved on the back of each half.

History
Originally, the perfect amulet was the key that gains entry into the Demon World. A gift that the Demon King gave to the corrupted humans who wanted power. After Sparda's Rebellion he used the amulet to seal off the two worlds. Sparda wears the amulet around his neck, as it is seen on him in his costumes for DMC1 and DMC3. He could use the amulet to access his powers, but only for a brief period. Centuries later, Sparda encounters Eva, who he then gives the amulet to. After his death, Eva gives two halves of the amulet, each to Vergil and Dante. Later in the events of DMC3, Vergil comes after Dante for his half of the amulet, in order to attain their Father's power. After a betrayal by Arkham, who manages to open the gate and get Sparda's power; Dante and Vergil defeated him, sending him back to earth. In a climatic battle, Dante and Vergil each receive their halves, Dante returns to the Human World, while Vergil stays behind. The amulets appear again in DMC1, as Dante still wears his around his neck and Vergil, now Nelo Angelo has his on him. After the first battle with Dante, Nelo sees Dante's half, and begins to react to the sight of it. Most likely Vergil's memories surfacing, affecting Mundus's control over him. In the final battle between the two brothers, Dante defeats Vergil, taking his half to enter the Demon World and finish off Mundus. At the end of the game, it can be seen around Trish's neck. as it seems Dante has entrusted it to her, though the amulet has not been seen or mentioned in DMC2 or DMC4. It's location is unknown as to date.

The Perfect Amulet is an ornate amulet which serves as a key to the Temen-ni-gru's gate to the Demon World[1][2], and is also necessary to awaken the Force Edge. A large red gem is set into the amulet, and it can be split into two halves. It was given as a gift to Eva by Sparda[2], and she gave the halves to their twin sons[3], Dante and Vergil, on their birthday.[4] Their names are engraved on the back of each half.[5]

Trivia
In Devil May Cry, both halves of the Perfect Amulet are wrought in silver, while in Devil May Cry 3, Dante's half is wrought in silver while Vergil's is wrought in gold. This discrepency has yet to be explained by CAPCOM.